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[0090/1094] drm/i915: Don't set DPFC_HT_MODIFY bit on CTG/ILK/SNB

Message ID 1413889294-31328-91-git-send-email-dheerajx.s.jamwal@intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Dheeraj Jamwal Oct. 21, 2014, 10:44 a.m. UTC 
From: Ville Syrjälä <ville.syrjala@linux.intel.com>

The ILK/SNB docs don't really mention the the DPFC_HT_MODIFY bit.
CTG docs clearly state that it should be set only when tracking
back buffer modification in persistent mode. The bit is supposed
to be set by software after the first CPU modification to the
back buffer, and it would get automagically cleared by the hardware
on the next page flip.

Since we only track front buffer modification we don't need to set
this bit. GTT modification tracking still appears to work on ILK
and SNB with the bit unset. I don't have a CTG to verify how that
behaves.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
(cherry picked from commit 4e41f3ac734794ac76c385b168abaf04d49131c6)

Signed-off-by: Dheeraj Jamwal <dheerajx.s.jamwal@intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c |    2 --
 1 file changed, 2 deletions(-)
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 91590b7..5d3f39e 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -159,7 +159,6 @@  static void g4x_enable_fbc(struct drm_crtc *crtc)
 
 	dpfc_ctl = plane | DPFC_SR_EN | DPFC_CTL_LIMIT_1X;
 	dpfc_ctl |= DPFC_CTL_FENCE_EN | obj->fence_reg;
-	I915_WRITE(DPFC_CHICKEN, DPFC_HT_MODIFY);
 
 	I915_WRITE(DPFC_FENCE_YOFF, crtc->y);
 
@@ -233,7 +232,6 @@  static void ironlake_enable_fbc(struct drm_crtc *crtc)
 	dpfc_ctl |= DPFC_CTL_FENCE_EN;
 	if (IS_GEN5(dev))
 		dpfc_ctl |= obj->fence_reg;
-	I915_WRITE(ILK_DPFC_CHICKEN, DPFC_HT_MODIFY);
 
 	I915_WRITE(ILK_DPFC_FENCE_YOFF, crtc->y);
 	I915_WRITE(ILK_FBC_RT_BASE, i915_gem_obj_ggtt_offset(obj) | ILK_FBC_RT_VALID);